Intrinsically noncombustible polymers without flame retardant additives: Sulfur-containing and bio-based benzoxazines

摘要

The benzoxazine monomers using 4,4'-thiobisphenol as phenol resource have been synthesized (the monomer is abbreviated as TBP-a for aniline as an amine reactant, TBP-fa for furfurylamine, and TBP-sa for stearylamine, respectively). Three sulfur-containing benzoxazines have the following characteristics: simple synthetic and purification methods, melting points close to those of bisphenol A and aniline-based benzoxazine (BA-a), and lower polymerization temperatures than BA-a. Poly(TBP-a) and poly(TBP-fa) are found to have excellent thermal properties, including high char yields and very low heat release capacities, while TBP-sa is used as a comparison. Newly developed thiobisphenol-based benzoxazines offer the possibility to develop halogen- and phosphorus-free flame retarding polymers that combine the high performance and low cost of commercially available raw materials. It further offers potential for developing greener, more environmentally benign materials than traditional flame retardant-added polymers.